JPS6186029A - Bending and bulging working method of pipe - Google Patents

Abstract

PURPOSE:To enable the bending and bulging work without any fold by bending the prescribed angle to the opposite side by the crushed part with crushed one part of a pipe wall and by bulging the pipe in the prescribed diameter with working from the inner side with its bent condition. CONSTITUTION:A punch 16 is fitted into the hole 18 of a die 14 with fitting a pipe stock 1 into the hole 17 of a pipe crushing device and one part F of the pipe wall of the part to be bent of the pipe 1 is crushed. A straight pipe wall part G is then brought into contact with the apex 24b of the crest part of the hole 24 with inserting the pipe 1 into the hole 24 of the die 21 of the pipe bending device and the pipe 1 is bent along the apex part 24b with inserting a punch 23 into the hole of the die 21. This pipe 1 is bulged in the prescribed diameter by a water pressure via a lateral pressure piston 29 after being located by the bulging die 28 of a bulging work device. The bending and bulging work of the necessary bent pipe having no fold is thus enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for bending and expanding a pipe by bending and expanding the pipe without creating wrinkles at the bent portion.

(Prior Art) As a conventional method for bending and expanding pipes, the following method has been used, for example. That is, Fig. 4+8)
, (as shown in BL, a straight raw material pipe 1 is placed on a rotary die 3 of a bending device 2, and is pressed from above with a punch 4 having an arcuate pipe contact surface 4a with a radius of curvature R□, The raw material pipe l is bent at a predetermined angle. In the figure, 5 is a band that supports the rotary die 3. Next, the bent raw material pipe la is expanded to a predetermined diameter by bulge processing. Fig. 5 shows this bulge processing. In this device, 7 is a bulge die, 8 is a side pressure piston that pressurizes the material pipe la from the inside via a hydraulic medium, and lb is an expanded pipe.

Note that the bulge diameter is divided into two parts by a plane parallel to the plane of the paper.

(Problems to be Solved by the Invention) However, in such a conventional method for bending and expanding pipes, when pressing and bending the raw pipe 1 from one side with the punch 4, the raw pipe 1 is bent. Compressive stress is generated on the pipe wall E on the inside in the bending direction, that is, on the side that is in contact with the punch 4, but since the inside of the raw pipe l is not pressurized, the pipe wall E is compressed toward the inside of the pipe. Bending wrinkles 10 occur. This wrinkle 10 is caused by the fact that when the bent material pipe 1a is expanded, the radius of curvature R2 of the expanded tube wall E on the inside of the bent portion is larger than the radius of curvature of the tube wall E at the time of bending, that is, the punch 4.
Since the radius of curvature R1 of the pipe abutting surface 4a is smaller than the radius of curvature R1 of the pipe abutting surface 4a, the amount of wrinkles further increases due to compressive stress, resulting in an unsatisfactory overlapping of 1lltll as shown in FIG.

(Means for Solving the Problems) This invention was made by focusing on the problems of the conventional art. a step of bringing the tube into close contact with the pipe wall;
Pipe bending comprising: bending the pipe at a predetermined angle in the direction of the pipe wall on the opposite side at the crushed portion; and pressurizing the pipe from the inside in the bent state to expand the entire pipe to a predetermined diameter. The above problems are solved by providing an expansion processing method.

(Example) The present invention will be explained below based on the drawings.

Figures 1+a+, (bl to 3) show an embodiment of the apparatus used to carry out the present invention.

Figure 1(a) shows a pipe crushing device, in which 14 is a die fixed on the bolster 15 of the press machine, and 16 is a die attached to the slide (not shown) of the press machine and vertically This is a punch that can approach and separate from the die I4 from above. The die 14 is provided with a horizontal hole 17 having the same diameter as the outer diameter d of the material pipe 1, and a vertical hole 18 communicating with the hole 17 and into which the punch 16 can be inserted. The tip (lower end) surface 16b of the punch 16 is horizontal to the extending direction of the hole 17, and the direction perpendicular to the extending direction of the hole 17 has a semicircular cross section as shown in FIG. , the corners are rounded r.The punch 16 is punched in a direction perpendicular to the extending direction of the hole 17, which is smaller than the effective width W in the extending direction of the hole 17 and the outer diameter d of the material pipe 1. The punch 16 has a thickness t of the die 14.
8 and can enter the axial center of the hole 17, as shown in FIG. 1(b). Figure 2 Ta), (
bl indicates a pipe bending device, 21 in the figure is a die fixed on the bolster 22 of the press machine, and the blade is attached to the slide (not shown) of the press machine and approaches and separates from the die 21 from vertically above. Possible punch.

The die 21 has a hole 24 into which a material pipe l can be inserted, and a vertical hole 25 communicating with this hole 24 into which a punch holder can be inserted.
and are provided. The hole U has the outer diameter d of the material pipe 1,
has the same width d, and the lower end surface 24a has a radius d.
, /2 arc surface. And this lower end surface 24
The entire portion a is in the shape of a mountain with an apex angle equal to the bending angle of the material pipe I, with the apex at the longitudinal center of the hole 24, and the apex portion 24b is formed in an arc shape with a radius of curvature R1. The shape of the punch blade is such that its tip (lower end) surface a is the curvature radius R1 of the chevron-shaped lower end surface apex 24 b of the hole 24 of the die 21.
It is formed in the same manner as the punch 16 of the vibrator crushing device, except that it is formed into an arcuate surface with a radius of curvature (R, +2p) larger by twice (2p) the wall thickness p of the material pipe 1 than the punch 16 of the vibrator crushing device. . FIG. 3 shows a bulging device for expanding the raw material pipe 1 to a predetermined diameter in a bent state, in which the blades are bulges and 4 is a side pressure piston.

First, the material pipe 1 is inserted into the hole 17 of the vibrator crushing device shown in FIGS. Then, the punch 16 is lowered and the die 14 is
As shown in FIGS. 1A and 1B, a part F of the pipe wall of the part of the material pipe 1 to be bent is crushed, and this part F is inserted into the pipe wall G on the opposite side. Closely contact.

At this time, since tensile stress is generated in the crushed tube wall F, wrinkles do not occur. After raising the punch 16, the raw pipe 1 with a part F of the pipe wall crushed is pulled out from the hole 17 of the die 14. Next, this material pipe 1 is inserted into the hole 24 of the die 21 of the pipe bending device shown in FIG. At this time, the straight pipe wall part G to which the part F of the pipe wall of the material pipe 1 is in close contact is the chevron-shaped top part 24 b of the lower end surface 24 a of the hole 24 .
Position it so that it is in contact with the Then, when the punch 23 is lowered, the punch blade passes through the hole 25 of the die 21 and passes through the bent portions F and G of the material pipe 1 to the lower end surface 2 of the hole 24.
The material pipe 1 is pressed against the chevron-shaped top 24b of the hole 24 as shown in FIGS.
Fold along the chevron-shaped top 24 b of a. At this time, the pipe walls F and G of the raw pipe 1 that are in contact with the chevron-shaped top 24b are squeezed from both sides by the chevron-shaped top 24b and the lower end surface 23a of the punch, so that they do not wrinkle. will never occur. After raising the ponchi edict, Figure 2 (
δ), material pipe 1 bent as shown in (b)
is taken out from the die 21 and attached to the bulge processing apparatus shown in FIG. 3 in the bent state. That is, the pipe 1 is positioned in the bulge die 28 divided by a plane parallel to the plane of the paper, and the lateral pressure pistons 29 are inserted from both ends. Then, water pressure is applied to the inside of the raw material pipe 1 from the openings at both ends thereof via the side pressure piston 29 to expand the raw material pipe 1 to a predetermined diameter. A compressive stress will be generated in the wall G (see FIG. 3). However, this tube wall G has no wrinkles in either the crushing process or the bending process, water pressure acts from the inside, and the outside is regulated by the mold surface 28a of the bulge die 28. Even if compressive stress occurs, the wall thickness only increases and no wrinkles occur.

On the other hand, since tensile stress is generated on the pipe wall F on the outside in the bending direction, wrinkles do not occur. Therefore, a neatly bent pipe (pipe bend) without wrinkles can be obtained.

(Effects of the Invention) As described above, according to the present invention, there are a process of crushing a part of the pipe wall at the part where the pipe is to be bent, and making the pipe arrive at the pipe wall on the opposite side of this part; A pipe bending and expansion process comprising: bending the crushed portion at a predetermined angle in the direction of the opposite pipe wall; and pressurizing the pipe from the inside in the bent state to expand the entire pipe to a predetermined diameter. method can be provided. According to this processing method, wrinkles do not occur in the pipe in any of the steps, so a neat bent pipe without wrinkles can be obtained.

[Brief explanation of the drawing]

FIGS. 1(a) and (bl to FIG. 3) show an example of each step in the method for bending and expanding a pipe according to the present invention, and FIG. 1(a) shows a method for crushing a pipe. Figure 1 (Tbl) is a front cross-sectional view of the main parts of the pipe crushing device used in the pipe folding process, and Figure 2 (a) is a front cross-sectional view of the main parts of the pipe bending device that bends the pipes. Front sectional view, Fig. 2 (bl is a sectional view taken along the line B-B in Fig. 2 (a), Fig. 3 is a front sectional view of the main part of the bulge processing device that expands the pipe, Fig. 4 (Jl) , (b) and FIG. 5 show a conventional method for bending and expanding pipes, and FIG. ) is a sectional view taken along the line B-B of FIG. ---Crushed pipe wall of the bent part of the one-material pipe, G----Pipe wall of the un-squashed side of the bent part of the material pipe.

Claims (1)

[Claims] A step of crushing a part of the pipe wall of the part of the pipe to be bent so as to bring it into close contact with the pipe wall on the opposite side of this part; A method for bending and expanding a pipe, comprising the steps of: bending the pipe at a predetermined angle; and processing the pipe from the inside in the bent state to expand the entire pipe to a predetermined diameter.